<!DOCTYPE html>
<meta charset="utf-8">
<style>
#inspected {
  color: red;
  --variable: blue;
  background-color: var(--variable);
  animation-name: black;
  margin: 10px;
  background: url("red green blue.jpg");
  --red: invalid;
  border-color: var(--red);
}
</style>
<div id="inspected">Inspected div</div>
